South Africa (SA), a resource limited setting with the world?s largest population of people living with HIV, has hundreds of thousands of perinatally HIV-infected (PHIV+) youth who are rapidly becoming adolescents. PHIV+ adolescents must contend with the negative effects of life-long viral infection and chronic inflammation on their neurodevelopment, medical status, mental health, and, for many, the demands of lifelong ART adherence ? placing them at risk for not achieving these important milestones. Neurocognitive impairment (NCI) is chief among these negative effects. NCI in PHIV+ adolescents most commonly affects the neurocognitive domains of working memory, executive function and processing speed. NCI can affect youth?s ability to perform in and complete school, interact successfully with peers and adults, find employment, initiate and maintain long-term relationships, and function independently. NCI can also interfere with adherence to medication, which is critical in HIV, and increase poor decision-making and greater HIV transmission risk behaviors (e.g., unprotected sex). PHIV+ youth in SA are also at risk for NCI due to numerous psychosocial problems that are very common in resource limited settings, such as poverty and poor education. The first step in addressing NCI in PHIV+ adolescents is detecting and diagnosing it, but doing so in South Africa is seriously hampered. Few neurocognitive tests and screening tests exist for the hundreds of thousands of PHIV+ youth in SA. The tests that do exist for PHIV+ youth in SA require highly trained personnel to administer and score, take several hours to administer, lack ecological validity to predict real-world outcomes, and many suffer from cultural biases because they were developed for and normed on youth in the US or Europe. Given how overburdened the SA healthcare system is and its reliance on task-shifting various components of care to lay health workers (LHWs), without accurate, clinically useful, and relatively brief NC tests that can detect NCI and meet the demands of task-shifting in RLSs, PHIV+ adolescents in SA will not be assessed, missing opportunities to detect NCI and intervene. NeuroScreen is a brief, easy-to- use app for Android devices to assess and screen for NCI that is designed to be administered by a wide range of non- expert healthcare personnel in clinical settings. The app contains nine neurocognitive tests assessing processing speed, executive functions, working memory, verbal memory, and motor speed. It is standardized and highly automated, requires minimal training to administer, and does not require record- keeping or scoring. The proposed study will validate NeuroScreen for use with PHIV+ adolescents in SA by (1) evaluating its internal validity, (2) sensitivity and specificity to detect NCI compared to a gold standard neuropsychological test battery, and (3) characterize PHIV+ youth performance on it in the context of medical and psychosocial factors. The study will also generate preliminary normative performance data among 13-17 year adolescents in SA. A neurocognitive assessment tool like NeuroScreen could be easily modified for use in other disease populations and regions of the world that rely on task-shifting.